GM ended up buying all, or at least part of, Isuzu. Their diesels are all Isuzu. The old Oldsmobile was a good diesel for what it was designed for, but people were looking for what it wasn't. Translation: They wanted a 454 big block, but they bought a Vega 120 four banger. That, plus the fact that they made it a 350 ci, so, of course, the know-it-alls claimed it was just a gas engine with diesel injectors in it.